The LiftMaster 41A5021 is an electronic garage door opener made by the LiftMaster company of Elmhurst, Illinois. LiftMaster is a division of The Chamberlain Group, which has been manufacturing garage doors, openers and accessories for over a century. The 41A5021 is a standard, remote-operated model that works on a chain and pulley system. If you are having problems with your LiftMaster garage door opener, you must first determine what the issues are, and then you can locate the cause.
Power or Operating Problems
Inspect your home circuit breakers or fuses to see whether one has tripped or blown, if your LiftMaster garage door opener fails to respond to commands. If one has, reset it in the "On" position and try your LiftMaster garage door again. Check the outlet you are using to power your LiftMaster by testing it with a lamp. If the lamp lights, there is power in the outlet and the cause must be elsewhere. Your LiftMaster has an internal shutoff switch that kicks in due to overuse. Allow a 15-minute reset period before looking for other causes of system failure.
Locate the emergency release handle if your LiftMaster is not functioning. The handle is located at the rear of the door opener trolley, and will take the form of a string and plastic handle. Operate the door manually as you would any other manual garage door. If you are outside the garage when the failure occurs, use the outside quick-release handle to switch the door to manual control. The manual door handle that came with your garage door is the quick-release handle.
Test the door control panel if your LiftMaster works only with the remote control. Use your screwdriver to remove the red and white wires from their respective terminals at the motor unit. Connect the two terminals with a piece of scrap rubber-coated wire to activate the door. If the door works, the possible culprits include improper wiring at the door switch, a short along the switch wiring due to a staple or other metallic intrusion, or a break somewhere in the wire. If the remote control will not work, try reprogramming it. If the door bar indicator is blinking, the remote block may be on and should be removed.
Provide an unobstructed path for the remote signal to travel if it seems the range is shorter than usual. Check the antenna at the rear of the garage door opener motor to see that it is fully extended and providing the longest range possible.
Try installing a LiftMaster vibration reduction kit if the operation noise of your garage door opener is disturbingly loud.
Opening & Closing
Check that nothing is pressing down on the remote control buttons, and disconnect the bell wire inside the control panel if your LiftMaster is opening and closing on its own. The cause may be a short in the wall switch, or a programming error in your remote. Reprogram the remote to eliminate that possibility.
Inspect the area above and below the door if it does not close or open all the way, or if the door reverses in mid-motion. If there is nothing blocking the movement of the door, adjust the travel limiters. The travel limiters are located at the side of the motor unit, and can be adjusted with the turn of your screwdriver. Turn to the left to lower the door height, and to the right to raise it.
Inspect the opener springs if your LiftMaster motor makes noise but the door does not move, or if there is motor strain during the closing or opening process. Pull the emergency release handle to disengage the motor, then contact LiftMaster customer service for repairs.
Test your safety reverse sensor if the door fails to close. The safety reverse sensor is located at either side of the garage door opening near the base of the door. If the sensor is aligned off-center, is blocked or is damaged, it may fail to function properly and will cause your LiftMaster to fail to close.
Replace your lightbulbs if the interior light feature of your LiftMaster opener fails to illuminate. Do not use bulbs larger than 75 watts. If the lights turn on and will not turn off, check that the switch has not been left in the "On" position.